I suddenly encountered this problem, and tried hundreds of solutions online and no one is helpful to me.And finally I tried one that is useful:
in the tool-option-- debugging --- general*un-tick option : "require source files to exactly match to the original version"
1."recompile/build the project before adding the break-point"
3.Build -- Configuration Manager ...and check if the project with the code you're trying to debug is checked for the current build configuration.
Build -- Configuration Manager ...